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Date: Tue, 8 Jul 2003 02:09:27 -0700
From: Luigi Rizzo <rizzo@icir.org>
To: Bruce M Simpson <bms@spc.org>
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References: <20030703002247.A2097@grosbein.pp.ru>
	<3F0310CE.5070302@tenebras.com> <3F03867A.79F82968@kuzbass.ru>
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In-Reply-To: <20030707201247.GG32325@spc.org>;
	from bms@spc.org on Mon, Jul 07, 2003 at 09:12:47PM +0100
cc: Eugene Grosbein <eugen@kuzbass.ru>
cc: net@freebsd.org
Subject: QoS/device API (was Re: ipprecedence)
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On Mon, Jul 07, 2003 at 09:12:47PM +0100, Bruce M Simpson wrote:
...
> With the increased interest in VoIP and similar these days, perhaps hardware
> DS/QoS support of this nature is something the project should explore?

the usual problem here is that if you want your mechanisms to be
useful, you should implement them in software first (even though
it has a performance impact), and then exploit the hw capabilities
when/if they are present and useful (e.g. on a slow link and fast
CPU, you don't care too much about separate hw queues).

The 'if_tx_rdy' dummynet trick that i mentioned does cover the
software part, and i believe it can be made reasonably cheap (i.e.
skip the function call if no pipes are registered to be clocked by
that interface) so that it will not harm performance in the general case.

If there is interest, i can look into doing this change and adding
this call to our device drivers.

	cheers
	luigi